There are some points on Earth for which the following is true:

Starting from one of these points, you can walk 1 km South, then 1 km East, then 1 km North, and you will wind up back where you started from.

One such point is the North Pole. Where are others?

Dulajanna--

You are on the right track. But as you said, you can't walk 1km east at the South Pole.

You can, however slightly north of the Pole. If you pick your spot carefully, you can start and end the Eastern leg in the same spot, in effect drawing a circle 1km in circumference [or any integral fraction thereof (1/2 km, 1/3 km, etc.)].

From any point on any one of these circles, a point 1km north would be a valid starting point to fulfill the original problem.

Posted by TomM on 2002-05-29 07:08:30